I know I beat on my 440source 500 cubic inch in my Daytona for 3 years (275+) passes running a best 8.60's@151mph. When I took it apart the block was cracked but never leaked and was still running 8.60's. The assembly check out GREAT and will be used by another Moparts member soon. I have a brand new 512 440source assembly that I bought years ago and may replace my 408 smallblock that's in my Duster soon. We are also on our 3rd race season with a starter that we bought from them. I also purchased 2 sets of their heads with zero problems and I bought a very nice set of valve covers from them that are still being used.